Power generators, in particular high-frequency generators, are usually supplied with power from a three-phase network which delivers 3×400 V at 50 Hz, for example. Due to weather influences, fluctuations on the load side, and other influences on the mains supply side, the mains voltage delivered by the three-phase network may have partial or total dips for varying time periods. This is particularly problematic if a plasma is used as the load that is supplied by the power generator. A plasma is dependent on the impedance of the power delivered by the power generator. If the power fails for some time, processes are carried out that cannot be directly reversed. For example, the plasma may go out, necessitating renewed ignition. If layers are produced using the plasma, the properties of the layer surfaces may be changed in an undesirable manner.